Field of the Invention
The present invention relates to a technique for segmenting an image into a plurality of regions and extracting relevant features of the image from the segmented regions.
Description of the Related Art
Conventionally, a method for extracting a global feature from an entire image (feature extraction method) using block segmentation has been known. In the conventional feature extraction method, a plurality of straight lines are drawn vertically and horizontally to segment an image into a plurality of blocks (regions), and a feature such as a mean value of color information and histogram is extracted from each block region. In this manner, a global feature of the entire image can be extracted.
Further, Japanese Patent Application Laid-Open No. 2006-202100 discusses a technique for extracting feature amounts of regions on radial lines and a circumference of a circular anti-counterfeiting mark to prevent forgery of banknotes.
In an image including a vanishing point, an edge is likely to exist at a distance measured radially from the vanishing point. Furthermore, an object is likely to be located on a concentric circle centered at the vanishing point. Thus, it is difficult to extract features appropriately by segmenting an image including a vanishing point into blocks and then extracting features therefrom.
Further, according to the technique discussed in Japanese Patent Application Laid-Open No. 2006-202100, only the feature amounts of the regions on the radial lines and the circumference of the anti-counterfeiting mark for preventing forgery of banknotes are extracted to determine whether the mark is genuine. Therefore, it is not sufficient for appropriate extraction of a global feature of an image including a vanishing point.